The present invention comprises a multi component cigarette filter assembly comprising a hollow filter tube with spaced apart solid fiber plugs inside the tube and granular filter material between the plugs, and more particularly to such an assembly where the solid fiber plugs are secured to interior portions of the tube by energy activated adhesive selectively applied only between the plugs and the tube.
U.S. application Ser. No. 11/268,291, filed Nov. 4, 2005, claiming the benefit of earlier filed provisional application Ser. No. 60/625,747, filed Nov. 5, 2004, describes and illustrates a vertical filter filling machine and process. The disclosure of each of these applications is incorporated herein by reference, and each application describes and illustrates a preferred filter tube of paper with hollow ends and a solid center of cellulose acetate or similar material for producing two multi cavity cigarette filters. The filter tube is vertically oriented and moves along a generally circular path where metered amounts of granular filter material are initially deposited in the tube against the solid center. Thereafter, a plug of cellulose acetate or similar material is placed in the tube to thereby seal the granular material in place. A second deposit of a different granular material is then placed in the tube and a second plug seals that material in place. Subsequently, the tube is inverted and the remaining half is filled with granular material and sealed in the same manner. Cutting the tube midway through the solid center thereof produces two individual multiple cavity cigarette filters. The assembled filter tube forms a two-up dual filter which when combined with wrapped tobacco rods at each end thereof ultimately produces two complete cigarettes when cut midway through the solid center. Each individual cigarette filter may have a length of 30 mm, but can be shorter or longer, if desired.
Fundamentally, the solid fiber plugs are retained within the hollow filter tube by frictional engagement between the exterior surface of the plugs and the interior surface of the hollow filter tube.